The influence of core structure and material on the noise level of a three-phase stacked transformer core is studied using model cores composed of high flux-density grain-oriented magnetic steels. The noise level at 1.7 T and 50 Hz decreases by slightly less than 2 dB with an increase of 0.01 T in B_8 of the core material and is lower by 2 dB with step-lap joints than with alternate-lap joints. The amount of higher harmonics in magnetostric- tive oscillation and magnetizing force of the core mater- ial show a strong correlation with the noise level.
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